Catalyst components for the polymerization of olefins and catalysts therefrom obtained

ABSTRACT

The invention relates to catalyst components, suiitable for the sprtion of homnopolymats and copolymene of ethylene having a broad molecular weight distribution (MWD), which comprise Ti, Mg, Cl, and are characterized by the following properties: surface area, determined by BET method, of lower than 100 m 2 /g, a total poroslty, measured by the mercury method, of higher than 0.25 cm 3 /g, a pore radius distribution such that at least 45% of the total porosity is due to pores with radius up to 0.1 μm.

[0001] The present invention relates to catalyst components for thepolymerization of olefins CH₂=CHR, wherein R is hydrogen or hydrocarbonradical having 1-12 carbon atoms. In particular, the invention relatesto catalyst components suitable for the preparation of homopolymers andcopolymers of ethylene having a broad molecular weight distribution(MWD), and to the catalysts obtained therefrom.

[0002] In particular the present invention relates to a solid catalystcomponent, comprising titanium magnesium and halogen, having sphericalmorphology and particular surface characteristics. Furthermore, thepresent invention relates to a process for preparing ethylenehomopolymers and copolymers characterized by a high melt flow ratio(F/E) value, which is the ratio between the melt index measured with a21.6 Kg load (melt index F) and the melt index measured with a 2.16 Kgload (melt index E), determined at 190° C. according to ASTM D-1238.Said ratio F/E is generally considered as an indication of the width ofmolecular weight distribution.

[0003] The MWD is a particularly important characteristic for ethylene(co) polymers, in that it affects both the rheological behavior andtherefore the processability of the melt, and the final mechanicalproperties. Polyolefins having a broad MWD, particularly coupled withrelatively high average molecular weights, are preferred in high speedextrusion processing and in blow molding, conditions in which a narrowMWD could cause melt fracture. As a consequence of this need, differentmethods have been developed trying to achieve this property.

[0004] One of those is the multi-step process based on the production ofdifferent molecular weight polymer fractions in single stages,sequentially formning macromolecules with different length on thecatalyst particles.

[0005] The control of the molecular weight obtained in each step can becarried out according to different methods, for example by varying thepolymerization conditions or the catalyst system in each step, or byusing a molecular weight regulator. Regulation with hydrogen is thepreferred method either working in solution or in gas phase.

[0006] A problem typically associated with the processes of this type isthat the different polymerization conditions used in the two steps canlead to the production of not sufficiently homogenous products,especially in cases of very broad molecular weight distributions. It isin fact difficult to obtain products having a high F/E ratio, forexample higher than 100, which when subjected to a transformationprocess, yield products with a low number of unmelt particles (gels). Inorder to solve or minimize this problem it would be important to have acatalyst capable of producing broad MWD polymers also in a singlepolymerization step. This would allow, in case still broader MWD isdesired, the use of less different polymerization conditions in thesequential polymerization process that would finally result in a morehomogeneous product.

[0007] EP-A-119963 discloses catalyst components obtained by thereaction between a titanium halide and MgCl₂-based carriers, containingfrom 1.5 to. 20% of residual -OH groups, which are obtained byspray-drying MgCl₂·EtOH solutions. The weight reaction ratio between thetitanium halide and the MgCl₂ of the carrier has to be kept within the0.001 to 2 range. The catalysts obtained however, are not able to givebroad MWD since the shear sensitivity of the polymers (which is theratio between the melt indices measured at weight of 20 kg and 2.16 kgat 190° C.) is about 25 (examples 4-5 and 8-9) although thepolymerization process comprises two polymerization step under differentconditions.

[0008] Moreover, the catalysts disclosed in this patent application arealways used in a suspension polymerization process, while nothing issaid about gas-phase polymerization. This latter kind of process isnowadays highly preferred due to both the high qualities of the productsobtained and to the low operative costs involved with it. It wouldtherefore be advisable to have a catalyst capable to produce broad MWDpolymers and having at the same time the necessary features allowing itsuse in the gas-phase polymerization processes.

[0009] In EP-A-601525 are disclosed catalysts that, in some cases areable to give ethylene polymers with broad MWD (F/E ratios of 120 arereported). Such catalysts, obtained by a reaction between a Ti compoundand a MgCl₂·EtOH adduct which has been subject to both physical andchemical dealcoholation, are characterized by a total porosity (mercurymethod) higher than 0.5 cm³/g, a surface area (BET method) lower than 70m²/g. The pore distribution is also specific; in particular in all thecatalysts specifically disclosed at least 50% of the porosity is due topores with radius higher than 0.1251μ. Although the width of MWD is insome cases of interest, the bulk density of the polymers obtained isrelatively low and this is probably due to non completely regular shapeof the polymer formed which is in turn caused by non-proper behavior ofthe catalyst during polymerization. Hence, it is still very important tohave a solid catalyst component capable of good performances in thegas-phase polymerization process (in particular capable of producinghigh bulk density polymer) and at the same time capable of givingpolymers with a very broad MWD.

[0010] It has now surprisingly been found a catalyst component whichsatisfies the above-mentioned needs and that is characterized bycomprising Ti, Mg, Cl, and by the following properties:

[0011] surface area, determined by BET method, of lower than 100 m²/g,

[0012] a total porosity, measured by the mercury method, of higher than0.25 cm³/g

[0013] a pore radius distribution such that at least 45% of the totalporosity is due to pores with radius up to 0.1 μm.

[0014] Preferably the catalyst component of the invention comprises a Ticompound having at least one Ti-halogen bond supported on magnesiumchloride in active form. The catalyst component may also contain groupsdifferent from halogen, in any case in amounts lower than 0.5 mole foreach mole of titanium and preferably lower than 0.3.

[0015] The total porosity is generally comprised between 0.35 and 1.2cm³/g, in particular between 0.38 and 0.9.

[0016] The porosity due to pores with radius up to 1 μm is generallycomprised between 0.3 and 1 cm³/g in particular between 0.34 and 0.8. Ingeneral terms the value of the porosity due to pores with radius higherthan 1 μm is rather limited with respect to the total porosity value.Normally this value is lower than 25% and in particular lower than 15%of the total porosity.

[0017] The surface area measured by the BET method is preferablylowerthan 80 and in particular comprised between 30 and 70 m²/g. Theporosity measured by the BET method is generally comprised between 0.1and 0.5, preferably from 0.15 to 0.4 cm³/g.

[0018] As mentioned above the catalyst of the invention show aparticular pore radius distribution such that at least 45% of the totalporosity is due to pores with radius up to 0.1 μm. Preferably, more than50%, and in particular more than 65% of the total porosity is due topores with radius up to 0.1 μm. If only the porosity due to pores withradius up to 1 μm is taken into account, the value of the porosity dueto pores with radius up to 0.1 μm is even higher, generally more than60%, preferably more than 70% and particularly more than 80%.

[0019] This particular pore size distribution is also reflected in theaverage pore radius value. In the catalyst component of the inventionthe average pore radius value, for porosity due to pores up to 1 μm, islower than 900, preferably lower than 800 and still more preferablylower than 700.

[0020] The particles of solid component have substantially sphericalmorphology and average diameter comprised between 5 and 150 μm. Asparticles having substantially spherical morphology, those are meantwherein the ratio between the greater axis and the smaller axis is equalto or lower than 1.5 and preferably lower than 1.3.

[0021] Magnesium chloride in the active form is characterized by X-rayspectra in which the most intense diffraction line which appears in thespectrum of the non active chloride (lattice distanced of 2,56Å) isdiminished in intensity and is broadened to such an extent that itbecomes totally or partially merged with the reflection line falling atlattice distance (d) of 2.95Å. When the merging is complete the singlebroad peak generated has the maximum of intensity which is shiftedtowards angles lower than those of the most intense line.

[0022] The components of the invention can also comprise an electrondonor compound (internal donor), selected for example among ethers,esters, amines and ketones. Said compound is necessary when thecomponent is used in the stereoregular (co)polymerization of olefinssuch as propylene, 1-butene, 4-methyl-pentene-1. In particular, theinternal electron donor compound can be selected from the alkyl,cycloalkyl and aryl ether and esters of polycarboxylic acids, such asfor example esters of phthalic and maleic acid, in particularn-butylphthalate, di-isobutylphthalate, di-n-octylphthalate.

[0023] Other electron donor compounds advantageously used are the1,3-diethers of the formula:

[0024] wherein R^(I), R^(II), the same or different from each other, arealkyl, cycloalkyl, aryl radicals having 1-18 carbon atoms and R^(III),R^(IV), the same or different from each other, are alkyl radicals having1-4 carbon atoms.

[0025] The electron donor compound is generally present in molar ratiowith respect to the magnesium comprised between 1:4 and 1:20.

[0026] The preferred titanium compounds have the formulaTi(OR^(v))_(n)X_(y-n), wherein n is a number comprised between 0 and 0.5inclusive, y is the valence of titanium, R^(V) is an alkyl, cycloalkylor aryl radical having 2-8 carbon atoms and X is halogen. In particularR^(V) can be n-butyl, isobutyl, 2-ethylhexyl, n-octyl and phenyl; X ispreferably chlorine.

[0027] If y is 4, n varies preferably from 0 to 0.02; if y is 3, nvaries preferably from 0 to 0.015.

[0028] A method suitable for the preparation of spherical components ofthe invention comprises the following steps:

[0029] (a) reacting a compound MgCl₂mR^(VI)OH, wherein 0.3 <m <1.7 andR^(VI) is an allyl, cycloalkyl or aryl radical having 1-12 carbon atoms,with a titanium compound of the formula Ti(OR^(V))_(n)X_(y-n), in whichn is comprised between 0 and 0,5, y is the valence of titanium, X ishalogen and R^(V) is an alkyl radical having 2-8 carbon atoms;

[0030] (b) reacting the product obtained from (a) with An Al-alkylcompound and

[0031] (c) reacting the product obtained from (b) with a titaniumcompound of the formula Ti(OR^(V))_(n)X_(y-n), in which n is comprisedbetween 0 and 0,5, y is the valence of titanium, X is halogen and R^(V)is an alkyl radical having 2-8 carbon atoms.

[0032] The compound MgCl₂·mR^(VI)OH is prepared by thermaldealcoholation of adducts MgCl₂·pR^(VI)OH, wherein p is equal to orhigher than 2 and preferably ranging from 2.5 to 3.5. It is especiallypreferred the use of adducts in which R^(VI) is ethyl.

[0033] The adducts, in spherical form, are prepared from molten adductsby emulsifying them in liquid hydrocarbon and thereafter solidifyingthem by quick cooling. Representative methods for the preparation ofthese spherical adducts are reported for example in U.S. Pat. No.4,469,648, U.S. Pat. No. 4,399,054, and W098/44009. Another suitablemethod for the spherulization is the spray cooling described for examplein U.S. Pat. Nos. 5,100,849 and 4,829,034. As mentioned above the soobtained adducts are subjected to thermal dealcoholation at temperaturescomprised between 50 and 150° C. until the alcohol content is reduced tovalues lower than 2 and preferably comprised between 0.3 and 1.7 molesper mole of magnesium dichloride.

[0034] In the reaction of step (a) the molar ratio Ti/Mg isstoichiometric or higher, preferably this ratio in higher than 3. Stillmore preferably a large excess of titanium compound is used. Preferredtitanium compounds are titanium tetrahalides, in particular TiCl₄ Thereaction with the Ti compound can be carried out by suspending thecompound MgCl₂·mR^(VI)OH in cold TiCl₄ (generally 0° C.); the mixture isheated up to 80-140° C. and kept at this temperature for 0.5-2 hours.The excess of titanium compound is separated at high temperatures byfiltration or sedimentation and siphoning. If the titanium compound is asolid, such as for example TiCi₃, this can be supported on the magnesiumhalide by dissolving it in the starting molten adduct.

[0035] In step (b) the product obtained from (a) is then reacted with analuminum-alkyl compound. The aluminum alkyl compound is preferablyselected from those of formula R^(VII) ₂AIX_(3-z) in which R^(VII) is aC₁-C₂₀ hydrocarbon group, z is an integer from 1 to 3 and X is halogen,preferably chlorine. Particularly preferred is the use of the trialkylaluminum compounds such as for example triethylaluminum,triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum and tris(2,4,4-trimethyl-pentyl)aluminum. Use oftris(2,4,4-trimethyl-pentyl) aluminum is especially preferred. It isalso possible to use mixtures of trialkylaluminum compounds withalkylaluminum halides, alkylaluminum hydrides or alkylaluminumsesquichlorides, such as AlEt₂Cl and Al₂Et₃Cl₃.

[0036] The reaction with the Al-alkyl compound with the product comingfrom (a) can be carried out in a hydrocarbon solvent at a temperaturebetween −10° C. and 130° C. Preferably the reaction is carried out at atemperature between 40 and 110° C. The molar ratio between the Al-alkylcompound and the product coming from (a) is not particularly critical.Generally the Al-alkyl compound can be used in molar ratios with thealcohol originally contained in the compound (a) from 0.01 to 100.

[0037] In the third step, the solid product coming from (b) is furtherreacted with a titanium compound of formula Ti(OR^(V))_(n)X_(y-n) inwhich n, R^(V), X and y have the same meaning given above. The specifictitanium compound and the reaction conditions can be identical to, ordifferent from, those used in the first step. Normally, the use of thesame titanium compound and the same reaction conditions is preferred.

[0038] The catalyst components of the invention form catalysts, for thepolymerization of alpha-olefins CH₂=CHR^(VIII) wherein R is hydrogen ora hydrocarbon radical having 1-12 carbon atoms by reaction with Al-alkylcompounds. In particular Al-trialkyl compounds, for exampleAl-trimethyl, Al-triethyl , Al-tri-n-butyl , Al-triisobutyl arepreferred. The Al/Ti ratio is higher than 1 and is generally comprisedbetween 20 and 800.

[0039] In the case of the stereoregular polymerization of α-olefins suchas for example propylene and 1-butene, an electron donor compound(external donor) which can be the same or different from the compoundused as internal donor is also generally used in the preparation of thecatalyst.

[0040] In the case in which the internal donor is an ester of apolycarboxylic acid, in particular a phthalate, the external donor ispreferably selected from the silane compounds containing at least aSi-OR link, having the formula R^(IX) _(4-n)Si(OR^(X))_(n), whereinR^(IX) is an alkyl, cycloalkyl, aryl radical having 1-18 carbon atoms,R^(X) is an alkyl radicar having 1-4 carbon atoms and n is a numbercomprised between 1 and 3. Examples of these silanes aremethyl-cyclohexyl-dimethoxysilane, diphenyl-dimethoxysilane,methyl-t-butyl-dimethoxysilane, dicyclopentyldimethoxysilann

[0041] It is possible to advantageously use also the 1,3 diethers havingthe previously described formula. In the case in which the internaldonor is one of these diethers, the use of an external donor can beavoided, as the stereospecificity of the catalyst is alreadysufficiently high. The spherical components of the invention andcatalysts obtained therefrom find applications in the processes for thepreparation of several types of olefin polymers.

[0042] For example the following can be prepared: high density ethylenepolymers (HDPE, having a density higher than 0.940 g/cm³), comprisingethylene homopolymers and copolymers of ethylene with alpha-olefinshaving 3-12 carbon atoms; linear low density polyethylene's (LLDPE,having a density lower than 0.940 g/cm³) and very low density and ultralow density (VLDPE and ULDPE, having a density lower than 0.920 g/cm³,to 0.880 g/cm³ cc) consisting of copolymers of ethylene with one or morealpha-olefins having from 3 to 12 carbon atoms, having a mole content ofunits derived from the ethylene higher than 80%; elastomeric copolymersof ethylene and propylene and elastomeric terpolymers of ethylene andpropylene with smaller proportions of a diene having a content by weightof units derived from the ethylene comprised between about 30 and 70%,isotactic polypropylenes and crystalline copolymers of propylene andethylene and/or other alpha-olefrns having a content of units derivedfrom propylene higher than 85% by weight; shock resistant polymers ofpropylene obtained by sequential polymerization of propylene andmixtures of propylene with ethylene, containing up to 30% by weight ofethylene; copolymers of propylene and 1-butene having a number of unitsderived from 1-butene comprised between 10 and 40% by weight.

[0043] However, as previously indicated they are particularly suited forthe preparation of broad MWD polymers and in particular of broad MWDethylene homopolymers and copolymers containing up to 20% by moles ofhigher α-olefins such as propylene, 1-butene, 1-hexene, 1 -octene.

[0044] In particular the catalysts of the invention are able to giveethylene polymers, in a single polymerization step, with a F/E ratiohigher than 100 and even higher than 120 that are indicative ofexceptionally broad MWD. The F/E ratio can be further increased byoperating in two sequential polymerization reactors working underdifferent conditions.

[0045] The catalyst of the present invention can be used as such in thepolymerization process by introducing it directly into the reactor.However, it constitutes a preferential embodiment the prepolymerizatiornof the catalyst. In particular, it is especially preferredpre-polymerizing ethylene or mixtures thereof with one or moreα-olefins, said mixtures containing up to 20% by mole of α-olefin,forrming amounts of polymer from about 0.1 g per gram of solid componentup to about 1000 g per gram of solid catalyst component. Thepre-polymerization step can be carried out at temperatures from 0 to 80°C. preferably from 5 to 50° C. in liquid or gas-phase. Thepre-polymerization step can be performed in-line as a part of acontinuos polymerization process or separately in a batch process. Thebatch pre-polymerization of the catalyst of the invention with ethylenein order to produce an amount of polymer ranging from 0.5 to 20 g pergram of catalyst component is particularly preferred.

[0046] The main polymerization process in the presence of catalystsobtained from the catalytic components of the invention can be carriedout according to known techniques either in liquid or gas phase usingfor example the known technique of the fluidized bed or under conditionswherein the polymer is mechanically stirred. Preferably the process iscarried out in the gas phase.

[0047] Examples of gas-phase processes wherein it is possible to use thespherical components of the invention are described in W092/21706, U.S.Pat. No. 5,733,987 and W093/03078. In this processes a pre-contactingstep of the catalyst components, a pre-polymerization step and a gasphase polymerization step in one or more reactors in a series offluidized or mechanically stirred bed are comprised.

[0048] Therefore, in the case that the polymerization takes place ingas-phase, the process of the invention is suitably carried outaccording to the following steps:

[0049] (a) contact of the catalyst components in the absence ofpolymerizable olefin or optionally in the presence of said olefin inamounts not greater than 20 g per gram of the solid component (A);

[0050] (b) pre-polymerization of ethylene or mixtures thereof with oneor more α-olefins, said mixtures containing up to 20% by mole ofα-olefin, forming amounts of polymer from about 0.1 g per gram of solidcomponent (A) up to about 1000 g per gram;

[0051] (c) gas-phase polymerization of ethylene or mixtures thereof withα-olefins CH=CHR, in which R is a hydrocarbon radical having 1-10 carbonatoms, in one or more fluidized or mechanically stirred bed reactorsusing the pre-polymer-catalyst system coming from (b).

[0052] As mentioned above, the pre-polymerization step can be carriedout separately in batch. In this case, the pre-polymerized catalyst ispre-contacted according to step (a) with the aluminum alkyl and thendirectly sent to the gas-phase polymerization step (c).

[0053] As mentioned above, in order to further broaden the MWD of theproduct, the process of the invention can be performed in two or morereactors working under different conditions and optionally by recycling,at least partially, the polymer which is formed in the second reactor tothe first reactor. As an example the two or more reactors can work withdifferent concentrations of molecular weight regulator or at differentpolymerization temperatures or both. Preferably, the polymerization iscarried out in two or more steps operating with different concentrationsof molecular weight regulator. In particular, when the catalysts of theinvention are used in this kind of process they are able to giveethylene polymers having exceptionally broad MWD while, at the sametime, maintaining a good homogeneity. Once used in the production offilms indeed, *the polymers showed a very good processability while thefilms obtained showed a very low number of gels.

[0054] The following examples are given in order to further describe andnot to limit the present invention.

[0055] The properties are determined according to the following methods:

[0056] Porosity and surface area with nitrogen: are determined accordingto the B.E.T. method (apparatus used SORPTOMATIC 1900 by Carlo Erba).

[0057] Porosity and surface area with mercury:

[0058] The measure is carried out using a “Porosimeter 2000 series” byCarlo Erba.

[0059] The porosity is determined by absorption of mercury underpressure. For this determination use is made of a calibrated dilatometer(diameter 3 mm) CD₃ (Carlo Erba) connected to a reservoir of mercury andto a high-vacuum pump (1-10² mbar). A weighed amount of sample is placedin the dilatometer. The apparatus is then placed under high vacuum (<0.1=m Hg) and is maintained in these conditions for 20 minutes. Thedilatometer is then connected to the mercury reservoir and the mercuryis allowed to flow slowly into it until it reaches the level marked onthe dilatometer at a height of 10 cm. The valve that connects thedilatometer to the vacuum pump is closed and then the mercury pressureis gradually increased with nitrogen up to 140 kg/cm². Under the effectof the pressure, the mercury enters the pores and the level goes downaccording to the porosity of the material.

[0060] The porosity (cm³/g), both total and that due to pores up to 1μM, the pore distribution curve, and the average pore size are directlycalculated from the integral pore distribution curve which is functionof the volume reduction of the mercury and applied pressure values (allthese data are provided and elaborated by the porosimeter associatedcomputer which is equipped with a “MILESTONE 200/2.04 ” program by C.Erba. MIE flow index: ASTM-D 1238 MIF flow index: ASTM-D 1238 Bulkdensity: DIN-53194 Fraction soluble in xylene: determined at 25° C.Effective density: ASTM-D 792

[0061] Determination of gel number: 1Kg of polymer is pelletized by aBandera TR15 pelletizer for 1 hour keeping the temperature at 230° C. inall the sections with the screw rotating at 50 rpm. The first 300 gramsof material are discarded while the remaining is introduced in aPlasticizers MKII film extruder with a 3000 mesh/cm² filter in which theprofile temperature was 260-260-260-270-270° C. and the screw rotationspeed was 30 rpm. The determination of the number of gels per m² iscarried out by visually detecting the number of gels having size higherthan 0.2mm on a piece of the extruded film (30×4 cm size) which isprojected by a projector, on the wall-chart with a magnificated scale.The counting is made on 3 different pieces of the same film and a finalnumber is given by the expression No=A/S where No is the number of gelsper m², A is the number of gels counted on 3 film pieces and S is theoverall surface in m² of the 3 films pieces examined.

EXAMPLES PREPARATION OF THE SPHERICAL SUPPORT (ADDUCT MgCl₂/EtOH)

[0062] A magnesium chloride and alcohol adduct was prepared followingthe method described in example 2 of U.S. Pat. No. 4,399,054, butworking at 2000 RPM instead of 10000 RPM.

[0063] The adduct containing about 3 mols of alcohol had an average sizeof about 70 μm with a dispersion range of about 45-100 μm.

EXAMPLE 1

[0064] Preparation of the Solid Component

[0065] The spherical support, prepared according to the general methodunderwent a thermal treatment, under N₂ stream, over a temperature rangeof 50-150° C. until spherical particles having a residual alcoholcontent of about 25% (0.69 mole of alcohol for each MgCl₂ mole) wereobtained. Into a 721 steel reactor provided with stirrer, 44 liters ofTiCl₄ at 0° C. and whilst stirring 2200 g of the support wereintroduced. The whole was heated to 130° C. over 60 minutes and theseconditions were maintained for a further 60 minutes. The stirring wasinterrupted and after 30 minutes the liquid phase was separated from thesettled solid. Thereafter 4 washings with anhydrous hexane (about 22liters) were performed two of which were carried out at 80° C. and twoat room temperature.

[0066] Then, after the addiction of 31 liters of anhydrous hexane, 11liters of a solution of tris(2,4,4-trimethyl-pentyl)aluminum (Tioa) inhexane (100 g/l) were introduced at room temperature into the reactorand stirred for 30 minutes. The liquid phase was separated from thesettled solid that was washed with 22 liters of hexane and with 22liters of heptane (twice for each other) at room temperature.

[0067] Thereafter a further treatment with 44 liters of TiCl₄ wasperformed in the same condition with respect to the first one, and after4 washings with anhydrous hexane, 2200 g of the spherical solidcomponent were obtained. After drying under vacuum at about 50° C., thesolid showed the following characteristics: Total titanium  4.6% (byweight) Ti^(III)  0.6% (by weight) Al 0.11% (by weight) Mg 17.0% (byweight) Cl 73.4% (by weight) OEt  0.3% (by weight) porosity (B.E.T.) 0.153 cm³/g surface area (B.E.T.)  50.6 m²/g total porosity (Hg)  0.692cm³/g, 70% of which was due to pores with radius up to 0.1 μm. Porositydue to pores with radius 0.552 up to 1 μm: Average pore radius: 0.0827μm surface area (Hg)  31.5 m²/g

[0068] Ethylene polymerization (HDPE)

[0069] Into a 10 liters stainless steel autoclave, degassed under N₂stream at 70° C., 4 liters of anhydrous hexane, 0.15 g of sphericalcomponent and 1.5 g of triisobutylaluminum (Tiba) were introduced. Thewhole was stirred, heated to 75° C. and thereafter 4 bar of H₂ and 7 barof ethylene were fed. The polymerization lasted 3 hours during whichethylene was fed to keep the pressure constant. 2120 g of polymer wasobtained having the following characteristics: MIE  0.12 g/10 minMIF/MIE 127.5 effective density 0.960 g/cm³ bulk density 0.355 g/cm³morphology spherical

[0070] 1 kg of the so obtained polymer has been subject to themeasurement of the gel number according to the procedure previouslydescribed and the result was 730 gel/m².

EXAMPLE 2

[0071] Preparation of the Solid Component

[0072] The spherical support, prepared according to the general methodunderwent a thermal treatment, under N₂ stream, over a temperature rangeof 50-150° C. until spherical particles having a residual alcoholcontent of about 15% (0.37 mole of alcohol for each MgCl₂ mole) wereobtained. Into a 2 1 glass reactor provided with stirrer, 0.5 liters ofTiCl₄ at 0° C. and whilst stirring 50 g of the support were introduced.The whole was heated to 60° C. over 15 minutes and these conditions weremaintained for a further 60 minutes. The stirring was interrupted andafter 10 minutes the liquid phase was separated from the settled solid.Thereafter 3 washings with anhydrous hexane (about 0.5 liters) wereperformed at room temperature.

[0073] Then, after the addiction of 1 liter of anhydrous heptane, 0.24liters of a solution of tris(2,4,4-trimethyl-pentyl)aluminum (Tioa) inhexane (250 g/l) were introduced at room temperature into the reactor.The reactor was heated at 50° C. and the solution was stirred for 60minutes. The liquid phase was separated from the settled solid that waswashed twice with 0.5 liters of hexane at room temperature.

[0074] Into the reactor, 0.5 liters of TiCl₄ and 0.5 liters of heptanewere introduced, the solution was heated at 100° C. and after 30 minutesand the liquid phase was separated from the solid component.

[0075] Then, 1 liter of TICl₄ was introduced into the glass reactor. Thewhole was heated to 130° C. over 30 minutes and these conditions weremaintained for a further 60 minutes. The stirring was interrupted andafter 10 minutes the liquid phase was separated from the settled solid.Thereafter 3 washings with anhydrous hexane at 60° C. and 3 washings atroom temperature were performed. After drying under vacuum at about 50°C., the solid showed the following characteristics: Total titanium  3.3%(by weight) Ti^(III)  1.0% (by weight) Al  0.4% (by weight) Mg 20.2% (byweight) Cl 72.7% (by weight) OEt  1.2% (by weight) porosity (B.E.T.) 0.298 cm³/g, surface area (B.E.T.)   2.2 m²/g

[0076] Ethylene Polymerization (HDPE)

[0077] Into a 4 liters stainless steel autoclave, degassed under N₂stream at 70° C., 1600 cc of anhydrous hexane, 0.02 g of sphericalcomponent and 0.3 g of triisobutylaluminum (Tiba) were introduced. Thewhole was stirred, heated to 75° C. and thereafter 4 bar of H₂ and 7 barof ethylene were fed. The polymerization lasted 2 hours during whichethylene was fed to keep the pressure constant. 225 g of polymer wasobtained having the following characteristics: MIE  0.14 g/10 minMIF/MIE 137.0 effective density 0.960 g/cm³ bulk density  0.40 g/cm³morphology spherical

EXAMPLE 3

[0078] Into a 1 1 glass reactor provided with stirrer, 0.8 liters ofTiCI₄ at 0° C. and whilst stirring 40 g of the support prepared asexplained into the example 3, were introduced. The whole was heated to130° C. over 15 minutes and these conditions were maintained for afurther 30 minutes. The stirring was interrupted and after 10 minutesthe liquid phase was separated from the settled solid. Thereafter 3washings with anhydrous hexane (about 0.8 liters) were performed at roomtemperature.

[0079] Then, after the addiction of 0.3 liter of anhydrous hexane, 37 ccof a solution of triethylauminum (Tea) in hexane (100 g/l) wereintroduced at room temperature into the reactor and stirred for 30minutes. The liquid phase was separated from the settled solid that waswashed three times with 0.4 liters of heptane at room temperature.

[0080] Into the reactor, 0.8 liters of TiCl₄ were introduced, thesolution was heated at 130° C. and after 30 minutes and the liquid phasewas separated from the solid component. Thereafter 3 washings withanhydrous hexane at 60° C. and 3 washings at room temperature wereperformed. After drying under vacuum at about 50° C., the solid showedthe following characteristics: Ti^(III)  2.7% (by weight) Al 0.52% (byweight) Mg 18.8% (by weight) Cl 71.2% (by weight) OEt  0.6% (by weight)porosity (B.E.T.)  0.239 cm³/g, surface area (B.E.T.)  43.1 m²/g totalporosity (Hg)  0.402 cm³/g, 85% of which was due to pores with radius upto 0.1 μm. Porosity due to pores with radius 0.359 up to 1 μm: Averagepore radius: 0.0369 μm surface area (Hg)  54.0 m²/g

[0081] Ethylene Polymerization (HDPE)

[0082] 0.02 g of the spherical component were used in ethylenepolymerization under the same conditions described in example 2.

[0083] 180 g of polymer were obtained having the followingcharacteristics: MIE  0.16 g/10 min MIF/MIE 152.0 effective density0.960 g/cm³ bulk density 0.414 g/cm³ morphology spherical

[0084] Comparison Example 4

[0085] Preparation of the Solid Component

[0086] The spherical support, prepared according to the general methodunderwent a thermal treatment, under N₂ stream, over a temperature rangeof 50-150° C. until spherical particles having a residual alcoholcontent of about 35% (1.1 mole of alcohol for each MgCl₂ mole) wereobtained. 2700 g of this support were introduced into a 60-1 autoclavetogether with 38 1 of anhydrous hexane. Under stirring and at roomtemperature 11.6 liters of hexane solution containing 100 g/l of AlEt₃were fed over 60 minutes.

[0087] The temperature was raised to 50° C. over 60 minutes and wasmaintained at that temperature for a further 30 minutes whilst stirring.The liquid phase was removed by filtration; the treatment with AlEt₃ wasrepeated twice again under the same conditions. The spherical productobtained was washed three times with anhydrous hexane and dried at 50°C. under vacuum.

[0088] The thus obtained support showed the following characteristics:porosity (Hg)   1.2 g/cm³ surface area (Hg)   18. m²/g OEt residual  5.%(by weight) Al residual  3.4% (by weight) Mg 20.1% (by weight)

[0089] Into a 72 1 steel reactor provided with stirrer 40 liters ofTiCl₄ were introduced; at room temperature and whilst stirring 1900 g ofthe above described support were introduced. The whole was heated to100° C. over 60 minutes and these conditions were maintained for afurther 60 minutes. The stirring was interrupted and after 30 minutesthe liquid phase was separated from the settled solid. Two furthertreatments were carried out under the same conditions with the onlydifference that in the first of these treatment it was carried out at120° C. and in the second at 135° C. Thereafter 7 washings withanhydrous hexane (about 19 liters) were carried out three of which werecarried out at 60° C. and 4 at room temperature. 2400 g of component inspherical form were obtained which, after drying under vacuum at about50° C., showed the following characteristics: Total titanium   8.2% (byweight) Ti^(III)   6.1% (by weight) Al   1.4% (by weight) Mg   16% (byweight) Cl  67.8% (by weight) OEt  0.3% (by weight) porosity (B.E.T.) 0.155 cm³/g, surface area (B.E.T.)  32.9 m²/g total porosity (Hg) 0.534 cm³/g, 40% of which was due to pores with radius up to 0.1 μm.Porosity due to pores with radius 0.475 up to 1 μm: Average pore radius:0.2294 μm surface area (Hg)    40 m²/g

[0090] Ethylene Polymerization (HDPE)

[0091] Into a 10 liters stainless steel autoclave, degassed under N₂stream at 70° C., 4 liters of anhydrous hexane, 0.02 g of sphericalcomponent and 1.2 g of triisobutylaluminum (Tiba) were introduced. Thewhole was stirred, heated to 75° C. and thereafter 4 bar of H. and 7 barof ethylene were fed. The polymerization lasted 3 hours during whichethylene was fed to keep the pressure constant. 1920 g of polymer wasobtained having the following characteristics: MIE  0.11 g/10 minMIF/MIE 105 effective density 0.960 g/cm³ bulk density 0.315 g/cm³

[0092] 1 kg of the so obtained polymer has been subject to themeasurement of the gel number according to the procedure previouslydescribed and the result was 9000 gel/m².

EXAMPLE 5

[0093] Preparation of HDPE by a Two Step Sequential PolymerizationProcess

[0094] Into a 4 liters stainless steel autoclave, degassed under N₂stream at 70° C., 2 liters of propane, 0.067 g of the sphericalcomponent prepared according to the procedure of Example 1 and 0.7 g oftriisobutylalunrinurn (Tiba) were introduced. The whole was stirred,heated to 75° C. and thereafter 2.5 bar of H₂ and 7 bar of ethylene werefed. The polymerization lasted 30 minutes during which 160 g ofpolyethylene were produced. After this period the autoclave was degassedand then a second step was performed with the same catalyst and underthe same conditions with the only difference that the hydrogen pressurewas 7 bar. This second step lasted 7 hours and gave 640 g ofpolyethylene.

[0095] The total 800 g therefore obtained had the followingcharacteristics: MIE 0.21 g/10 min MIF/MIE 212 effective density 0.960g/cm³ bulk density 0.41 g/cm³ Gel number 500 /m²

1. Catalyst components for the polymerization of olefins CH₂=CHR^(VIII),wherein R^(RIII) is hydrogen or hydrocarbon radical having 1-12 carbonatoms, comprising Ti, Mg, Cl and optionally OR groups, and characterizedby the following properties: surface area, determined by BET method, oflower than 100 m²/g, a total porosity, measured by the mercury method,of higher than 0.25 cm³/g and, a pore radius distribution such that atleast 45% of the total porosity is due to pores with radius up to 0.1μm.
 2. Catalyst components according to claim 1 in which the catalystcomponent comprises a Ti compound having at least one Ti-halogen bondsupported on magnesium chloride in active form.
 3. Catalyst componentsaccording to claim 1 containing groups different from halogen, in amountlower than 0.3 mole for each mole of titanium.
 4. Catalyst componentsaccording to claim 1 in which the total porosity is between 0.35 and 1.2cm³/g.
 5. Catalyst components according to claim 4 in which the totalporosity is between 0.38 and 0.9.
 6. Catalyst components according toclaim 1 in which the porosity due to pores with radius up to 1 μm isbetween 0.3 and 1 cm³/g.
 7. Catalyst components according to claim 6 inwhich the porosity due to pores with radius up to 1 μm is between 0.34and 0.8.
 8. Catalyst components according to claim 4 in which the valueof the porosity due to pores with radius higher than μm is lower than25% with respect to the total porosity.
 9. Catalyst components accordingto claim 8 in which the value of the porosity due to pores with radiushigher than μm is lower than 15% with respect to the total porosity. 10.Catalyst component according to claim 1 in which the surface areameasured by the B.E.T. method is preferably lower than 80 m²/g. 11.Catalyst component according to claim 1 in which the surface area isbetween 30 and 70 m²/g.
 12. Catalyst component according to claim 1 inwhich the porosity measured by the BET method is generally comprisedbetween 0.1 and 0.5 cm³/g.
 13. Catalyst component according to claim 12in which the porosity is from 0.15 to 0.4 cm³/g.
 14. Catalyst componentaccording to claim 1 in which more than 50% of the total porosity is dueto pores with radius up to 0.1 μm.
 15. Catalyst component according toclaim 1 in which more than 65% of the total porosity is due to poreswith radius up to 0.1 μm.
 16. Catalyst components according to claim 1in which the average pore radius value, for porosity due to pores up to1 μm, is lower than 0.09μm.
 17. Catalyst components according to claim16 in which the average pore radius value, for porosity due to pores upto 1 μm, is lower than 0.08μm.
 18. Catalyst components according toclaim 17 in which the average pore radius value, for porosity due topores up to 1 μm, is lower than 0.07μm.
 19. Catalyst componentsaccording to claim 1 in which the titanium compound has the formulaTi(OR^(V))_(n)X_(y-n), wherein n is a number comprised between 0 and 0.5inclusive, y is the valence of titanium, R^(V) is an alkyl, cycloalkylor aryl radical having 2-8 carbon atoms and X is chlorine.
 20. Catalystcomponents according to claim 19 in which y is 3 or 4, and n is
 0. 21. Aprocess for the preparation of the catalyst components of claim 1comprising the following steps: (a) reacting a compound MgCl₂mR^(VI)OH,wherein 0.3 ≦m ≦1.7 and R^(VI) is an alkyl, cycloalkyl or aryl radicalhaving 1-12 carbon atoms, with a titanium compound of the formulaTi(OR^(V))_(n)X_(y-n), in which n is comprised between 0 and 0,5, y isthe valence of titanium, X is halogen and R^(V) is an alkyl radicalhaving 2-8 carbon atoms; (b) reacting the product obtained from (a) withAn Al-alkyl compound and (c) reacting the product obtained from (b) witha titanium compound of the formula Ti(OR^(V))_(n)X_(y-n), in which n iscomprised between 0 and 0,5, y is the valence of titanium, X is halogenand R^(V) is an alkyl radical having 2-8 carbon atoms.
 22. Processaccording to claim 21 in which he compound MgCl₂mR^(VI)OH is prepared bythermal dealcoholation of adducts MgCl₂·pR^(VI)OH, wherein p is a numberhigher than
 2. 23. Process according to claim 21 in which the titaniumcompound used in step (a) and (c) is TiCl₄.
 24. Process according toclaim 21 and 22 in which R^(VI) is ethyl.
 25. Process according to claim21 in which the aluminum alkyl compound of step (b) is selected fromthose of formula R_(z)AlX_(3-z) in which R is a C₁-C₂₀ hydrocarbongroup, z is an integer ranging from 1 to 3 and X is chlorine. 26.Process according to claim 25 in which the aluminum alkyl compound is atrialkyl aluminum compounds selected from the group consisting oftriethylaluminum, triisobutylaluminum, tri-n-butylaluminum,tri-n-hexylaluminum, tri-n-octylaluminum.
 27. Process according to claim26 in which the aluminum alk-yl compound is tri-n-octylaluminum. 28.Catalysts for the polymerization of olefins comprising the product ofthe reaction between an aluminum alkyl compound and a catalyst componentaccording to one or more of the claims 1-20.
 29. Pre-polymerizedcatalyst for the polymerization of olefins obtained by pre-polymerizingethylene or mixtures thereof containing one or more α-olefins, with acatalyst according to claim 28 and thereby forming amounts of polymerfrom 0.1 up to 1000 g per gram of solid catalyst component.
 30. Processfor the polymerization of olefins CH₂=CHR^(VIII), wherein R^(VIII) ishydrogen or hydrocarbon radical having 1-12 carbon atoms, carried out inthe presence of a catalyst according to any of the claims 28-29. 31.Process for the preparation of broad molecular weight distributionethylene polymers having a F/E ratio higher than 100 characterized inthat it is carried out in the presence of a catalyst according to claims28-29.
 32. Process according to claim 31 in which the F/E ratio ishigher than
 120. 33. Process according to claim 31 characterized by thefact that it is carried out more than one step working under differentpolymerization conditions.
 34. Polymer products obtainable from theprocesses according to any of the claims 30-33.